we have this on rockclimbing.com... they call it the "hostile" but its very cool, just goes by e-mail or PM I used it recently when moving out to AZ I found a climbing partner who was up for drinks... but they also have free room's listed and other goodies.

might be a cool feature of the new site Ian. As I know the RC.com site is built in php, although I think they use phpbb for their board, maybe its a hack only available for that bb